The invention relates to an injector device having a locking means that prevents a driving means from expelling a substance before a predetermined amount of pressure has been achieved within the device.
The traditional needleless injectors include the basic design: a housing with an inner power unit, a medication unit, and a nozzle. The function of the power unit is to pump the medication into an under-plunger cavity of the medication unit chamber and to expel the medication through the nozzle.
Some needleless injectors are powered by a pneumatic drive. These injectors may include an injection chamber having a piston and nozzle, a pneumatic cylinder having a power pneumatic piston, a gas distribution unit, a pipeline for the supply of compressed air into the pneumatic cylinder, and an exhaust for the release of compressed air into the atmosphere. Significant disadvantages prevail in this type of injector. First, the time for increasing a pressure to drive the pneumatic piston is relatively long. A dead volume in the injector cavity requires time to fill and achieve the required pressure. This initially allows jet formation with insufficient kinetic energy to properly pierce the subject""s skin and results in poor overall injection quality both in terms of the depth (transdermal, subcutaneous, or intramuscular) and the amount of medication delivered. To this end, a device that prevents the driving means from expelling the medicine before the required amount of pressure has built is needed.
Another disadvantage of the described needleless injector is the need to return the power piston and other moveable parts to their initial position. Typically, this is accomplished using a mechanical spring. Mechanical springs increase the dimensions and mass of the jet injector and are a common mode of failure.
Accordingly, there is a need in the art of needleless injector devices to solve the problem of early injection. More particularly, there is a need for an injector that increases the quality of an injection, decreases the loss of medicine on the skin""s surface, and decreases the dimensions and mass of a jet injector.
The foregoing problems are solved and a technical advance is achieved by the present invention. Disclosed is an injector assembly having driving means for injecting a substance into a subject and locking means for retaining the driving means. More particularly, the present invention relates to an injector assembly comprising a piston assembly having a piston and a spring, a lock assembly having at least one roller, at least one roller retainer, and an annular groove, the lock assembly configured to engage the piston assembly, an injection chamber, wherein the piston assembly is configured to drive a substance out of the injection chamber, and a pneumatic pressure unit detachably attached to the piston assembly by at least one path.